An intravascular medical device may be attached to a distal end of an inner catheter and held within an outer catheter for introduction into a patient. The intravascular medical device may, for example, be a vascular or vena cava filter for capturing embolic material in the blood flow, a stent, an embolic filter, an angioplasty balloon, a drug delivery device, or similar such minimally invasive intravascular device.
The inner and outer catheters may be introduced into a patient over a guidewire. Upon positioning the intravascular medical device within the vasculature at the site of treatment, the outer catheter is retracted from the inner catheter to release the device from the outer catheter. Because the inner and outer catheters are typically made from a longitudinally flexible material to allow navigation of the catheter assembly through the vasculature during insertion to the site of treatment, neither of the inner or outer catheters may have good resistance to kinking. The kinking resistance may not be an issue during catheter insertion because the inner and outer catheters are concentrically disposed and may be disposed over a guide wire. However, upon reaching the site of treatment, kinking of the inner catheter during retraction of the outer catheter may present problems to a medical professional during a procedure
An intravenous catheter introducer is known in the art and includes a pair of telescoping members disposed between a hub on a distal end and a flash housing on a proximal end of the telescoping members. Prior to catheter introduction, the telescoping members are retracted such that the hub and flash housing are juxtaposed and a sharpened cannula tip extends from a distal end of the catheter introducer. The cannula tip is used to pierce a blood vessel such that the peripheral intravenous catheter can be introduced into the blood vessel over the cannula. The catheter introducer is subsequently withdrawn exposing the sharpened cannula tip now soiled with blood from the patient. The sharpened cannula tip is subsequently covered by a portion of the catheter introducer by pulling the hub and the housing apart until the telescoping members lock out further movement.
Kinking of the cannula is not an issue in catheter introducers because friction of the hub and housing being pulled apart provides a tension force to the cannula. In contrast, kinking can be a problem for a catheter hub having inner and outer catheter members because the action of withdrawing the outer catheter over the inner catheter frictionally provides a longitudinally compressive force to the inner catheter. Accordingly, there remains a need for an improved catheter hub that addresses the kinking problem.